An adjustable construction square is provided that comprising an elongated blade member and an elongated cross member. An end of the cross member has a contour, and an end of the blade member has a contour. The adjustable construction square includes a clamping jig that enables the construction square to be quickly secured into a desired angular position. The clamping jig includes a clamping device, a wedge device, and an arm that work in combination to secure the adjustable construction square in a desired position.